There is not much difference in hp or torque at all..not worth the money and time involved unless you already need an inframe...On the only bus I have done it on it went from 155 rwhp old and wore out I thought to 168 rwhp rebuilt .new liners pistons ,4 valve head,dual exhaust..etc..factory specs show about the same 2 valve vs 4 valve,more for reliability than power..gg04

Logged

If you personally have not done it , or saw it done.. do not say it cannot be done...1960 4104 6L71ta ddec Falfurrias Tx

The 2 valve head actually has better lugging power than the 4 valve head-although the 4 valve head breathes better at higher rpm, so it can put out more horsepower. If your engine is running alright and you're satisfied with the performance, I'd leave well enough alone. If when you do overhaul it, I would rebuild it to turbo specs with an air to air intercooler. Then the black smoke at high altitudes would be eliminated. Good Luck, TomC

IF overhaul time go to crosshead pistons turbo valves in a 4valve head,dry air filters,N65 brown tag inj 5and1half inch intake,dw/ls gov. I have 4.11 gears ,24.5 tires engine rpm at 2375 ,I run with the v8s all day long and have for 9years Just a Maine point of view good luck chuck

only place they get me is off the line.....couple miles down the road I can catch and pass most......450hp doesn't really ammount to top speed when the comapny has the buses goverend at the speed limit......

Well, Guys, Here is where I am at. The coach is at DD shop. My previous post on the main bearing problem is now modified according to the Shop foreman yesterday. They got the 20 under bearings and tried to install them, but it locked the crank! So I don't know where in Sam Hill we are with this engine now? If the crank checks close to 20 under, and 20 under bearings won't fit, it looks to me like the crank has to come out. Anyone here got any ideas of what to do with this? Bill T.